Comorbidity and cost burden among ischemic stroke inpatients aged 60 years and older in middle-high-income region in China: a multicenter cross-sectional study.

Background: Older adults with ischemic stroke (IS) are prone to develop comorbidities, thus worsening clinical outcome and intensifying cost burden. Limited studies have revealed evidence linking types of combined diseases with economic burden in IS patients. In this study, prevalent combined diseases and clusters of comorbidity among IS patients aged≥ 60 years were identified. Meanwhile, we explored the combined diseases significantly correlated with incremental hospital costs, aiming to promote the individualized and comprehensive management of IS patients. Methods: The study was a multicenter, cross-sectional study based on clinical data of IS patients (aged ≥60 years) obtained from three tertiary centers of PLA General Hospital between 2018 and 2023. Patients were stratified into three age groups: 60-69 years, 70-79 years, and ≥80 years. Descriptive analyses were performed to show patient number, the composition of combined diseases, and medical costs. Apriori association rules mapped the clusters of comorbidity. Spearman correlation analysis combined with age-stratified quantile regression identified cost-intensive health conditions. Results: Apriori correlation analysis revealed a dominant cardio-metabolic-cluster and the intermediary role of diabetes. Hypoproteinemia aggregated with pulmonary infection and anemia, forming a clinically significant malnutrition-infection-anemia triad. The healthcare costs were highest in advanced older adult group despite an overall expenditure declining from 2018 to 2023. Spearman correlation and quantile regression analyses showed correlation between incremental costs and malnutrition-infection-anemia triad, especially at higher cost quantiles. Pulmonary infection was associated with relatively higher cost burdens in patients aged ≥80 years, with significant estimated increases of about ¥5,953, ¥8,538, ¥13,810, and ¥18,945 at the 10th, 25th, 50th, and 75th percentiles. Hypoproteinemia tended to correspond to the significant rise in costs at the 50th percentile for patients aged 60-69 years ( Conclusion: This study identified three prevalent comorbidity clusters in the study population: cardio-metabolic, diabetes-mediated multi-organ injury, and malnutrition-infection-anemia clusters. From the perspective of healthcare cost, pulmonary infection, hypoproteinemia, and anemia might represent the principal cost-intensive clusters of comorbidity, especially in those aged ≥80 years. The persistent cost-age gradient necessitates risk-stratified resource allocation. Implementation of geriatric-specific comorbidity control protocols, particularly targeting the identified clusters with high costs, may optimize both clinical outcomes and healthcare economics in aging populations.